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Introduction
Heart failure is the final common pathway for many cardiovascular
diseases whose natural history results in symptomatic or asymptomatic
left ventricular dysfunction. The cardinal manifestations of heart
failure are dyspnea, fatigue and fluid retention. These symptoms
can impair the functional capacity and quality of life of the
affected individuals. In the US, approximately 2,50,000 patients
die as a direct or indirect consequence of heart failure each
year, and the number of deaths due to heart failure has increased
6-fold during the past 40 years. The risk of death is 5-10% annually
in patients with mild symptoms and increases to as high as 30-40%
annually in patients with advanced disease.
Prevalence
The prevalence of heart failure increases with age. Ageing of
the population and the prolonged survival of patients with a variety
of cardiovascular diseases that culminate in ventricular dysfunction
ensure that the magnitude of the heart failure problem will substantially
worsen in the next decade. Approximately 1.5-2% of the US population
has heart failure and the prevalence increases to 6-10% in patients
aged above 65 years.
Main causes of heart failure
- Coronary artery disease
- Hypertension
- Valvular heart disease (especially aortic and mitral disease)
- Cardiomyopathy
Compensatory changes in heart failure
| Activation of the sympathetic nervous system |
Release of antidiuretic hormone |
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Release of atrial natriuretic peptide |
| Activation of the renin angiotensin system |
Chamber enlargement |
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Myocardial hypertrophy |
| Increased heart rate |
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Classification of heart failure
The functional status of patients with heart failure is most commonly
assessed using the
New York Heart Association (NYHA) classification. Patients can
be assigned to 1 of 4 functional classes depending on the degree
of effort needed to elicit symptoms. This classification is widely
used but lacks sensitivity to detect small but important changes
in clinical status.
| NYHA
Class |
Symptoms |
| Class I |
No limitation of physical activity |
| Class II |
Slight limitation of physical activity |
| Class III |
Marked limitation of physical activity |
| Class IV |
Unable to carry out physical activity without
discomfort |
Types of heart failure
Congestive heart failure can be broadly subdivided into two distinct
forms:
1. Diastolic dysfunction or diastolic heart failure
2. Systolic dysfunction or systolic heart failure
A patient with systolic heart failure commonly has a left ventricular
ejection fraction less than 30%, while in diastolic heart failure,
there is impaired left ventricular relaxation or filling (diastolic
dysfunction), with normal or even supernormal contraction (systolic
function). Thus unlike diastolic dysfunction, the ejection fraction
is normal in systolic dysfunction.
Factors aggravating heart failure
- Myocardial ischemia or infarct
- Dietary sodium excess
- Excess fluid intake
- Medication noncompliance
- Arrhythmias
- Intercurrent illness (e.g. infection)
- Conditions associated with increased metabolic demand
(e.g. pregnancy, anaemia, thyrotoxicosis, excessive physical
activity)
- Administration of drug with
- negative inotropic properties
- fluid retaining properties (e.g. NSAIDs, corticosteroids)
- Alcohol
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